This invention relates generally to solenoid-actuated valves, and more specifically it relates to a method for controlling the thickness of an air gap that exists between the armature and a stationary part of the valve when the solenoid is de-energized.
The thickness of the air gap that exists in the magnetic circuit of a solenoid-actuated valve when the solenoid is de-energized is a major influence on solenoid performance. The thickness of the air gap affects the response time and pull-in force. In a solenoid-actuated valve that uses a push pin between the solenoid armature and the valving element, the thickness of the solenoid de-energized air gap has heretofore been controlled by pre-measuring various components of the assembly and then on the basis of these measurements, selecting a push pin of suitable length to achieve the desired air gap thickness in the final assembly. The proper push rod length is usually achieved either by selection from a group of different length push rods or else by altering the length of an oversized push rod. These procedures limit the efficiency with which such valves can be mass produced.
The present invention relates to a new and improved method for attaining the desired solenoid de-energized air gap in a more efficient manner. The invention contemplates the use of a standard length push pin. The amount of protrusion of an end of the push pin from a stationary part of the assembly is measured at a certain point in the fabrication process. Then before the armature is assembled, a depression whose depth is based on the push pin protrusion measurement is coined into the end of the armature that is to bear against the protruding end of the push pin. When the armature is assembled, the protruding end of the push pin seats in the depression that has been formed in the end of the armature with the result that the air gap between this end of the armature and the stationary part from which the push pin protrudes is the desired thickness. The process is well-suited for automated operation so that maximum production efficiencies can be attained.
The foregoing, as well as additional features, advantages, and benefits of the invention, will be seen in the ensuing description and claims which should be considered in conjunction with the accompanying drawing. The best mode conceived by the inventors for the practice of the invention is disclosed.